如何使用subprocess.call()获得进程运行的输出?
传递一个StringIO。StringIO对象的stdout给出以下错误:
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/subprocess.py", line 444, in call
return Popen(*popenargs, **kwargs).wait()
File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/subprocess.py", line 588, in __init__
errread, errwrite) = self._get_handles(stdin, stdout, stderr)
File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/subprocess.py", line 945, in _get_handles
c2pwrite = stdout.fileno()
AttributeError: StringIO instance has no attribute 'fileno'
>>>
我有如下的解决方案。它捕获被执行的外部命令的退出码、stdout和stderr:
import shlex
from subprocess import Popen, PIPE
def get_exitcode_stdout_stderr(cmd):
"""
Execute the external command and get its exitcode, stdout and stderr.
"""
args = shlex.split(cmd)
proc = Popen(args, stdout=PIPE, stderr=PIPE)
out, err = proc.communicate()
exitcode = proc.returncode
#
return exitcode, out, err
cmd = "..." # arbitrary external command, e.g. "python mytest.py"
exitcode, out, err = get_exitcode_stdout_stderr(cmd)
我这里也有一篇关于它的博客文章。
编辑:解决方案已更新到一个新的，不需要写入temp. files。
关键是使用subprocess.check_output函数
例如，下面的函数捕获进程的stdout和stderr，并返回它们以及调用是否成功。它兼容Python 2和3:
from subprocess import check_output, CalledProcessError, STDOUT
def system_call(command):
"""
params:
command: list of strings, ex. `["ls", "-l"]`
returns: output, success
"""
try:
output = check_output(command, stderr=STDOUT).decode()
success = True
except CalledProcessError as e:
output = e.output.decode()
success = False
return output, success
output, success = system_call(["ls", "-l"])
如果你想以字符串而不是数组的形式传递命令，请使用以下版本:
from subprocess import check_output, CalledProcessError, STDOUT
import shlex
def system_call(command):
"""
params:
command: string, ex. `"ls -l"`
returns: output, success
"""
command = shlex.split(command)
try:
output = check_output(command, stderr=STDOUT).decode()
success = True
except CalledProcessError as e:
output = e.output.decode()
success = False
return output, success
output, success = system_call("ls -l")
subprocess.call()的输出应该只被重定向到文件。
你应该使用subprocess.Popen()来代替。然后你可以传递subprocess。PIPE用于stderr, stdout和/或stdin参数，并使用communication()方法从管道中读取:
from subprocess import Popen, PIPE
p = Popen(['program', 'arg1'], stdin=PIPE, stdout=PIPE, stderr=PIPE)
output, err = p.communicate(b"input data that is passed to subprocess' stdin")
rc = p.returncode
原因是subprocess.call()使用的类文件对象必须有一个真实的文件描述符，因此实现了fileno()方法。仅仅使用任何类似文件的对象都不能达到目的。
更多信息请看这里。
对于python 3.5+，建议使用subprocess模块中的run函数。这将返回一个CompletedProcess对象，您可以很容易地从中获得输出和返回代码。
from subprocess import PIPE, run
command = ['echo', 'hello']
result = run(command, stdout=PIPE, stderr=PIPE, universal_newlines=True)
print(result.returncode, result.stdout, result.stderr)
我最近才知道如何做到这一点，这里有一些来自我当前项目的示例代码:
#Getting the random picture.
#First find all pictures:
import shlex, subprocess
cmd = 'find ../Pictures/ -regex ".*\(JPG\|NEF\|jpg\)" '
#cmd = raw_input("shell:")
args = shlex.split(cmd)
output,error = subprocess.Popen(args,stdout = subprocess.PIPE, stderr= subprocess.PIPE).communicate()
#Another way to get output
#output = subprocess.Popen(args,stdout = subprocess.PIPE).stdout
ber = raw_input("search complete, display results?")
print output
#... and on to the selection process ...
现在，命令的输出存储在变量“output”中。"stdout = subprocess. "PIPE”告诉类从Popen内部创建一个名为“stdout”的文件对象。据我所知，communication()方法只是作为一种方便的方式来返回您所运行的进程的输出和错误的元组。此外，该进程在实例化Popen时运行。
我有如下的解决方案。它捕获被执行的外部命令的退出码、stdout和stderr:
import shlex
from subprocess import Popen, PIPE
def get_exitcode_stdout_stderr(cmd):
"""
Execute the external command and get its exitcode, stdout and stderr.
"""
args = shlex.split(cmd)
proc = Popen(args, stdout=PIPE, stderr=PIPE)
out, err = proc.communicate()
exitcode = proc.returncode
#
return exitcode, out, err
cmd = "..." # arbitrary external command, e.g. "python mytest.py"
exitcode, out, err = get_exitcode_stdout_stderr(cmd)
我这里也有一篇关于它的博客文章。
编辑:解决方案已更新到一个新的，不需要写入temp. files。
